Reduction gearing



I REDUCHON GEARING.

APPLICATION FILED HAY 2- 192]- 1,434,965. Patented Nov. 7, 1922.

11m nwgm/dt I VENTOR ATTORNEY Patented Nov. 7, 1922.

UNITED srA'rEs PATENT creme; I

HENRY F. SCHMIDT, 0F SWABTHMOBE, PENNSYLVANIA, ASSIGNOR T0 WESTINGHOUSE ELECTRIC & MANUFACTURING OO A CQRPGRATION-OE ,PENNSYLVANIA.

REDUCTION GEARING.

ori i al applicationfiled August 31, 1917, Serial No 189,217. -I Jividedendthis application filed may 2, v 1921.. Serial N0. -466,,059.

To all jwkom it o nag concern Be it known that I, HENRY F. SCHMIDT, a citizen of the United States, and a resident of Swarthmore, in the county of Delaware and State of Pennsylvania, have invented a I new and useful Improvement in Reduction Gearin v Seriali i lo. 189,217, filed August 31, 1917), of which the followingis a specification.

My invention relates to reduction gearing,

" particularly of thetype intended for reducingthespeed of steam turblnes, and has for itsobject to provide apparatus of (the character designated whichshall be capable of counteracting any end thrust which may be imposed thereon in normal operation,

' well as othsecuri'ng equalization of tooth pressures.

Apparatus embodying features of my invention is illustratedon the accompanying drawings, forming a part ofthisapplication, in which the single figure isasectional action; however, it is necessarythat the tooth pressures in the two pairs of helical View ofaturbine and reductiongear sholwingmy improvement applied thereto.

In situations requiring the transmission of high power at high speeds, itisnecessary that gearinghaving adequate strength shall be employed. Opposed helical or herring-bone gearing has frequently been used for this purpose on account of the fact that there is a continuous overlapping of tooth meshing gears be balanced or equalized in order to secure satisiactory operation. It

, is obviousthat, if end thrust is [imposed upon'one of the gear members, the condition of equalized pressure is disturbed and itv thereforebecomes necessary to'provide some meansfor counteracting the end thrust so that the condition of equalized tooth pressures may be preserved. Accordingly, I have devised gearing of the characteixdes ignated which is inherently capable of counteracting end thrust, which maybe imposed upon one of the gear members, in; or

der to equalize tooth pressures;

(which is a division of application Reterring 110W more particularly to the drawing 'for ,a detailed description of my invention, agear case e is'shown havingreductiongearing therein comprising a pinion member 5 meshing with a gear (member '6. A turbine casing 7 is shown unitary with the gear casing 4.

The pinion ,member 5 includes reversely inclined helical gear portions 8 and 9 carried by the pinion shaft 10 journaled in bear ngs 11 and 5.2 carried by the ,gear case. The plnlon portions 8 and 9 mesh with the gear portions 13 and 14 respectively of the driven gear Gsecured to the driven shaft 15 Ournaled in bearings 16 and 17 carried by the gear case 4. A thrustjbearing 18 is associated with the shaft 15 in order to take end thrust,-should the shaft be used in conjunction with an element, for example, a ship propeller, which, 'in operation, develops ndthrii "The pinionshaft 10 extendsbeyond the gear case tend into the turbine casing T, the overhanging end thereof being provided with a'turbine rotor disc 20 provided upon its periphery "with a row of buckets or blades 21. As illustrated, theturbine is of v the well known reentry type and comprises a steam inletQQ communicating with one or more nozzles 23 designed to change the pressure energy of motive fluid into velocity energy and such nozzle ornozzlesdischarge high-velocity motive fluid directly against the blades 21. After passage between the blades 21 and having a portion or its velocity energy abstracted thereby, motive fluid enters the [redirecting chamber or chambers24ewherein its direction islchanged so that it may bejagain impinged against the row of blades, thereby providing for the abstraction ofthe remaining available portion of the ,velocity energy. Exhaust motive fluid "fiowsthroughthe exhaust outlet 25 arranged at one side loft -the overhung turbine rotor disc 20, therebyallowing for the formation, ofa relatively,largeexhaust outlet which will permit the exhaust to flow ing against external pressures, it will be ap- I parent that atmospheric pressure on one side of the runner 27 will predominate over the low pressure existing on the turbine side of the runner and that the, shaft 12 will there-' fore have thrust pressure towards the right imposed upon it. i In accordance with my invention, I have, therefore, provided pinion and gear por tions 9 and 14; which are relatively longer than the pinion and gearportions 8 and 13 in order to counteract the effect of thrust resulting from the difference in pressures onopposite sides of the runner 27 and totherefore secure an equalization of tooth pressures. With gears employing the herring bone arrangement of gear teeth, this unbalanced thrust pressure is taken up by one set of gear teeth, and, consequently that set is subject to materially greatertooth pres sure than theother set. For the purpose of equalizing the tooth pressures and uniformly distributing the working pressure over the two sets of teeth, I contemplate making the tooth faces of the two sets of unequal length. For example, in the drawing, the tooth faces of the set of pinion and gear tooth faces 9. and. 14 may bemade approximately twice the length of the set of tooth faces 8 and 13. It will, of course, be apparent that the difference in length of the tooth faces of the two sets will depend upon the lateral thrust encountered.

It is to be understood that my design of gearing may be employed'wherever its use may be advantageous. Hence, in its broader aspects, my invention is not limited for use in connection with a steam turbine, the latter usehaving been described somewhat in detailin order to indicate one example of application of my invention. It will be apparent. to those skilled in the art that one pair of meshing pinion and gear portions may be made longer than the other pair in order to counteract any lateral thrust imposed by any means upon either of the shafts associated with the gearing. For example, mechanical thrust may be imposed upon the shaft 12 due to other gearing, or propeller or other thrust imposed upon the shaft 15 of the gear which may be taken care of in a similar manner.

WVhile I have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications, without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

What I claim is: I 1. In a gearing device, the combination of a shaft, means connected to the shaft and imposing end thrust on the latter in operation, a first gear connected :to the shaft and having opposed sets of helical teeth, and a second gear having opposed sets of helical teeth meshing with the teeth of the first gear, the tooth faces of one pair of meshing sets of'helical teeth being longer than the tooth faces of the other pair to'count'er'act the end thrust of said means and to secure equalization of tooth pressures;

2. In a reduction gear, the combination of a drivin shaft, driving means connected to the driving shaft and imposing end thrust on'the latter in operation, a driving pinion connected to the driving shaft and having sets of opposedhelical teeth, and a driven gear having sets of opposed helical teeth meshing with the pinion teeth, the tooth faces of one pair of meshing sets of helical teeth being longer than the tooth faces of the other pair to counteract the end thrust of said driving means and to secure equalization of tooth pressures.

3. In combination with the driving and drivengear of a transmission gearing, a turbi ne rotor element mounted on the shaft of the driving gear, and gear'teeth formed in two oppositely inclined sets on said gears with the teeth faces of different length in the two sets for the purpose of taking up the lateral thrust occasioned by the turbine and of equalizing tooth pressures between the two sets. Y

4. In combination in a geared turbine unit, a driving gear having two sets of gear teeth with the tooth faces of one setlonger than the tooth faces of the other set, a driven gear having correspondingly formed gear teeth meshing with the teeth of tlie driving gear and a turbine mounted on the shaft of the driving .gear and subjecting the gear to a lateral thrust.

5. In a geared turbine system, a rotor, a shaft co-axial with the rotor and connected thereto, a" double helical pinion on said shaft, the oppositely inclined parts of said pinion being of unequal length whereby the pressure per unit length of tooth of the intermeshing double helical pinion will be uniform, substantially as described.

6. In a geared turbine system a rotor, a shaft co-axial With the rotor and connected thereto, a double helical pinion on said shaft,

the oppositely inclined parts of said pinion being of unequal length whereby the longitudinal thrust of the turbine rotor is balanced by an equal and opposite longitudinal thrust of the double helical pinion when power 10 p HENRY F. SCHMIDT. 

